不同剂量褪黑素腹腔注射对松果体切除术后鸡脊柱侧凸罹患率的影响

背景:鸡松果体切除可以导致脊柱侧凸,研究表明腹腔内注射褪黑素可降低其脊柱侧凸的发生率,但何种剂量的褪黑素可以产生这种效果还不清楚。目的:应用松果体切除来抑制鸡褪黑素的分泌,通过给予不同浓度的褪黑素制剂来观察其脊柱侧凸的发生率。设计:随机对照实验研究。地点和对象:实验于第二军医大学实验动物中心实施。雌性国产小绍兴鸡50只(第二军医大学实验动物中心提供,清洁级)。干预:将鸡50只按随机数字法分为5组,每组10只。对照组鸡在出生后3d时行松果体切除术,在控制白天12h光照(光照度为500Lx)、夜间12h完全黑暗(光照度为0～5Lx)条件下饲养。其余4组鸡在孵化后3d时行松果体切除术后,分别腹腔注射5,10,20和40mg/kg剂量的褪黑素制剂,2次/d,控制光照同对照组。主要观察指标:3个月后观察各组鸡脊柱侧凸的发生率及平均Cobb角。结果:3个月时共有25只鸡发生了的脊柱侧凸。对照组,5,10,20,和40mg/kg组中脊柱侧凸的发病数分别为6,5,5,4和5只。平均Cobb角为26.7°,23.5°,21.7°,24.5°,23.2°。5,10,20,和40mg/kg组与对照组在脊柱侧凸的罹患率和平均Cobb角上无明显差异。结论:给予不同剂量的褪黑素并不能降低脊柱侧凸的罹患率和侧凸的严重程度。

Impact ofintraperitoneal injection with melatonin at different doses on the attack rate ofscoliotic deformity in pinealectomized chickens

BACKGROUND: Pinealectomy can induce scoliosis in chickens. It had reported that intraperitoneal injection of melatonin could reduce the incidence of scoliosis in the pinealectomized chickens; however, what dose of melatonin can generate this effect has not been demonstrated.OBJECTIVE: To apply pinealectomy to inhibit the secretion of melatonin in chickens and to observe the incidence of scoliosis through the administration of melatonin at different concentrations.DESIGN: A randomized controlled study.SETTING and PARTICIPANTS: The study was conducted in Center for Laboratory Animals, Second Military Medical University. Fifty domestic Shaoxing chickens(clean degree) were obtained from the Center for Laboratory Animals, Second Military Medical University.INTERVENTIONS: The 50 chickens were randomly divided into 5 groups with 10 chickens each. Pinealectomy was performed in each control group when the chickens were 3-day-old, which were fed under the condition of light-dark(12 hours: 12 hours) cycle, 500 Lx in daytime and 0-5 Lx in nighttime after surgery. Pinealectomy was also performed in the chickens of the rest four groups on the 3rd day after their incubations. Chickens of the rest four groups were treated with intraperitoneal injection of Melatonin at 5, 10,20 and 40 mg/kg respectively twice a day. The feeding condition of the chickens in the rest four groups was the same as the control group.MAIN OUTCOME MEASURES: The incidence of scoliosis and the mean Cobb' s angle in chickens of each group were observed after 3 months.RESULTS: Scoliosis was developed in 25 chickens during 3 months. The chickens developing to scoliosis in control group, 5, 10, 20 and 40 mg/kg melatonin groups were 6, 5, 5, 4 and 5 with the mean Cobb' s angle of 26.7°,23.5°, 21.7°, 24.5° and 23.2° respectively. There were no significant differences in incidence and mean Cobb' s angle between 5, 10, 20 and 40 mg/kg melatonin group and control group.CONCLUSION:Administration of melatonin of different doses cannot reduce the incidence and the severity of scoliosis in pinealectomized chickens.